Colonies are encrusting, multiserial and sheet-like, often quite large in size. The apparent ancestrula is ascophoran, identical to zooids from later astogeny but smaller, about 0.36 mm long by 0.28 mm wide, and buds one distal and two distolateral zooids.
Autozooids are slightly elongate, rounded-rhomboidal in outline shape, moderately large, about 0.54-0.65 mm long by 0.35-0.46 mm wide in colonies from the Coralline Crag (cf. Recent material for which Zabala et al. 1993 quoted measurements of 0.48-0.76 mm long by 0.43-0.65 mm wide). The frontal shield is convex, finely granular and lacks pseudopores but is pierced marginally by small, subcircular areolar pores, usually arranged in a single row but sometimes with additional pores at the proximal end of the zooid. The primary orifice is wider than long, about 0.11 mm long by 0.15 mm wide, has two strong condyles close to the proximolateral corners, and contains a low, concave lyrula, often partly hidden by the prominent, acute umbo. Oral spines are invariably 6 in number. Zooid basal walls contain an uncalcified window. The ovicell is recumbent on the distal zooid, small, about 0.15 mm long by 0.25 mm wide, and has an imperforate, granular ectooecial surface.
Avicularia are lacking.
Kenozooids are occasionally present. They are sealed by a convex, cryptocystal wall that is granular and contains multiple rows of peripheral areolar pores.
This species was identified by Busk (1859) as Lepralia peachii Johnston and subsequently as Escharella immersa (Fleming, 1828) by Lagaaij (1952). Neither of these names is appropriate (see Bishop & Hayward 1989, p. 32) and it was left to Zabala et al. (1993) to introduce E. acuta for Recent material attached to deep-water corals from the western Mediterranean which is apparently the same as the species from the Coralline Crag Fm. Note, however, that the autozooids are somewhat larger in Recent than Coralline Crag colonies, and four rather than six oral spine bases are visible in fertile zooids.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Suffolk, UK.
Also recorded by Lagaaij (1952) from the Scaldisian of Oosterhout, The Netherlands (see Bishop & Hayward 1989, figs 129-131), and by Zabala et al. (1993) from the Recent of Blanes Canyon, western Mediterranean at a depth of 180-350 metres.